1. Field of the Invention
The present invention relates to a system and a method for diagnosing abnormalities in a plant control system to specify a device which is an abnormality cause by inputting characteristics of an abnormal control state in a plant such as a turbine plant.
2. Description of the Related Art
Generally, a steam turbine of a thermal power plant adjust a rotating speed, load torque, an increase rate of the rotating speed by controlling steam supplied to the turbine.
FIG. 9 is a diagram showing a steam flow of a representative steam turbine and a configuration of a device for controlling the flow.
Steam out of a boiler 101 flows through a main stop valve 102 and a control valve 103 which are arranged in series to drive a high-pressure turbine 104. The steam that has worked on the high-pressure turbine 104 is increased in temperature by a reheater 105, and then flows through a reheat stop valve 106 and an intercept valve 107 which are arranged in series to rotate an intermediate-pressure turbine 108. The steam out of the intermediate-pressure turbine 108 rotates a low-pressure turbine 109, and then flows to a condenser 110. A generator 111 serially connected to the turbines 104, 108 and 109 generates power by a constant rotating speed.
With this configuration, by controlling the plurality of steam valves 102, 103, 106 and 107, rotating speeds of the turbines 104, 108 and 109 are controlled to target rotating speeds.
When abnormalities occur in the steam valves or the like constituting the plant control system, follow-up with a required load becomes impossible. For example, the rotating speeds of the turbines 104, 108 and 109 are not set constant, inevitably causing hunting or the like, generating an abnormality symptom of the control system. When abnormalities deteriorate more, a protective device operates to stop the turbines.
Regarding such an abnormality symptom which does not necessarily stop the turbines, it is important to diagnose which of devices such as the steam turbines is abnormal to find countermeasures.
Conventionally, when an abnormality occurs in the control state of the turbine plant, a plant user has investigated a cause of the abnormality based on an operation manual or experience. When the abnormality cannot be solved by the plant user, a solution of the problem has been sought by making an inquiry to a manufacturer, reporting the abnormal state to ask for diagnosis, or asking for immediate dispatch of engineers.
In most cases, the manufacturer that has received the inquiry listens to characteristics of the abnormal state, and accordingly a field engineer or a control system designer estimates an abnormality cause and makes on-the-spot investigation.
In such a case, in the inquiry of the abnormal state by telephone or the like from the user, there is frequently a shortage of information regarding understanding of the characteristics of the abnormal state, resulting in a long time of narrowing-down cause devices in most cases.
Especially for a plant user at a remote place, engineer dispatch takes considerable time and costs.
Reference Patent Document (Jpn. Pat. Appln. KOKAI Publication No. 08-263135)
Thus, in the conventional control system diagnosis of the turbine plant caused by the turbine control device (steam valve or the like), information understanding such as characteristic understanding of a phenomenon or understanding of a running state when the abnormality occurs is insufficient in most cases. Because of this information shortage, in the manufacturer/service company or the like that has been asked to make an abnormality diagnosis, the engineer must take various cases into consideration to determine the cause of the abnormality. It requires considerable time and labor to solve the problem.
Additionally, there is a demand for diagnoses or the like regarding relatively minor daily abnormalities.
Thus, a primary diagnosis is first executed by a relatively simple method to narrow down target devices. An engineer may perform a detailed diagnosis or investigation as occasion demands. Accordingly, both of the request side and the service side can deal with the problem at low costs within a short time.
Because of the aforementioned conventional situations, there is a demand for a system for automatically making a primary diagnosis, in a relatively simple manner regarding abnormalities of the control system.